Clear silicone microemulsions

Abstract

Spontaneously formed highly stable clear water-in-oil microemulsions containing only small amounts of water can be prepared by combining and simply hand shaking (i) 0.1 to 9 percent by weight of water; (ii) greater than 80 percent by weight of a volatile cyclic alkyl siloxane or volatile linear alkyl siloxane; and (iii) 3 to 10 percent by weight of certain silicone polyether surfactants. The microemulsions are useful in personal care applications.

What is claimed is:  
     
       1. A water-in-oil microemulsion comprising (i) 0.1 to 9 percent by weight of water; (ii) greater than 80 percent by weight of a cyclic alkyl siloxane oil having the formula (R 2 SiO) p  or a linear alkyl siloxane oil having the formula R 3 SiO(R 2 SiO) q SiR 3  in which R is an alkyl group containing 1-6 carbon atoms, p is 3-6, and q is 0-5; and (iii) 3 to 10 percent by weight of a silicone polyether having a formula selected from the group consisting of                    
       where R1 represents an alkyl group containing 1-6 carbon atoms; R2 represents the radical —(CH 2 ( a O(C 2 H 4 O) b (C 3 H 6 O) c R 3 ; x has a value of 0-3; y has a value of 1-3; z has a value of 0-2; m has a value of 3-5; n is one; a has a value of 0-6; b has a value of 2-6; c has a value of 0-3; and R3 is hydrogen, a methyl radical, or an acyl radical; the water-in-oil microemulsion containing domains of oil or water having an average diameter of less than 100 nanometer (0.1 micron/1,000 angstrom Å). 
     
     
       2. A microemulsion according to  claim 1  in which the alkyl siloxane is present in the amount of 81 to 96.9 percent by weight. 
     
     
       3. A microemulsion according to  claim 1  in which the alkyl siloxane is present in an amount greater than 85 percent by weight. 
     
     
       4. A microemulsion according to  claim 1  in which the alkyl siloxane is octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, or a mixture of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane. 
     
     
       5. A personal care product containing the microemulsion of  claim 1 . 
     
     
       6. A method of treating hair or skin comprising applying to the hair or skin the microemulsion or a composition containing the microemulsion of  claim 1 .